"From 1926-1930 I did post graduate research under Alfred Weber at the Institut für Sozial-und Staatswissenschaften, Heidelberg, mainly in the Sociology of science. At the same time I began to collaborate with Karl Mannheim who, a few years older than I, was at that time lecturer in Sociology at Heidelberg."

source:

Reinhard Blomert: Intellektuelle im Aufbruch, München 1999: Hanser, S. 235